Output pathways from the rat superior colliculus mediating approach and avoidance have different sensory properties.

摘要: Neuroanatomical studies have demonstrated that the two major descending pathways from superior colliculus arise regionally segregated, distinct, cells of origin. Stimulation and lesion implicated crossed tecto-reticulo-spinal projection in approach movements towards novel stimuli whereas ipsilateral pathway appears to be involved control avoidance escape-like behaviours. The present electrophysiological study attempted characterise sensory properties antidromically identified origin these anaesthetised rats. We found contralaterally projecting predorsal bundle (PDB) efferents were primarily somatosensory while cuneiform (CNF) was visual. PDB cells, mainly intermediate layers, responded principally vibrissal stimulation with their overlying visual fields optimally stimulated by small dark moving objects lower rostral lateral field. In contrast, most CNF located rostromedially, greatest contribution responsive upper A significant proportion showed no response discs but fired vigorously ‘looming’ stimuli. Ethological considerations suggest are appropriate stimulus characteristics for a system controlling behaviour an animal such as rat where predators generally appear above prey is on ground.